1. Field of the Invention
The subject matter of the invention is a fuel pump comprising a driven impeller that rotates in a pump housing and has, on its sides, guide vanes that delimit a ring of vane chambers, partial ring-shaped ducts arranged on both sides in the region of the guide vanes in the pump housing and which form, with the vane chambers, and delivery chambers for delivering the fuel. An inlet duct opens into the one delivery chamber, and the other delivery chamber opens into an outlet duct, and vane chambers which lie opposite one another are connected to one another.
2. Description of Prior Art
Such fuel pumps according to the principle of a side duct pump are used to deliver fuel from a fuel container to an internal combustion engine of a motor vehicle and are therefore known. When the impeller wheel rotates, the fuel is drawn in via the inlet duct and raised to a relatively high pressure level as the fuel passes through the partial ring-shaped ducts. At the end of the partial ring-shaped ducts, which can extend over an angular region of 300° to 330°, the fuel is delivered, via the outlet duct and the electric motor of the fuel pump, to a supply line that conducts the fuel to the internal combustion engine. The guide vanes in the delivery chambers generate in this context a circulation flow which runs transversally with respect to the direction of movement of the guide vanes and which exits in the radially outer region of the guide vane and enters the partial ring-shaped duct, flows from the radial outer side to the radial inner side in the partial ring-shaped duct, leaves the partial ring-shaped duct radially on the inside and enters a vane chamber of the impeller again radially on the inner side. Half the circulation flow is therefore distributed to the partial ring-shaped duct and half to the vane chambers. The partial ring-shaped ducts end in the region of the outlet duct. While the outlet-side duct merges to a greater or lesser extent with the outlet duct, the inlet-side duct decreases its cross-sectional area to zero. This decreasing of the cross-sectional area usually occurs over an angular range of up to 40°. A disadvantage with these fuel pumps is that they generate a considerable noise level, which is disruptive, in particular when mounted in a fuel container of a motor vehicle.